1. Technical Field
Various embodiments of the present invention relate generally to a gap-fill polymer for filling fine pattern gaps, and more particularly to a gap-fill polymer having a low dielectric constant and excellent gap filling properties, and to a method for fabricating a semiconductor device using the same.
2. Related Art
In recent years, semiconductor devices have become larger in size and the integration density thereof has increased. According to this tendency, the density of circuit elements and interconnections on substrates has increased, thus causing undesirable electrical interactions such as circuit shorts and cross-talks.
To minimize such interactions, a process for insulating semiconductor devices has been employed which includes a gap-fill or trench-fill process performed using a metal having a higher conductivity than silicon dioxide and a dielectric material having a low dielectric constant (low-k) of less than 3.0.
For conventional semiconductor devices having a line width of 2× or more, a gap-fill process based on step coverage, which uses chemical vapor deposition (CVD) and atomic layer deposition (ALD), and a gap-fill process which uses a deposition-etching-deposition, are generally performed.
In recent years, as semiconductor devices having a line width of 2× or less have been required, there has been proposed a gap-fill process employing a polysilsesquioxane-based insulating film having a dielectric constant of about 2.5-3.1, which can be formed by a spin-on-deposition (SOD) process, instead of an SiO2-based insulating film which has a dielectric constant of 4.0 and which can be formed using chemical vapor deposition (hereinafter referred to as “CVD”) (see Patent Documents 1 to 3).
Meanwhile, as the distance between semiconductor devices gradually decreases and the aspect ratio of semiconductor devices increases, there is a problem in that voids and cracks may occur in the gap-fill regions of the semiconductor devices due to the deterioration in step coverage and the bending of the semiconductor devices during conventional gap-fill processes performed using the CVD and ALD processes, thus adversely affecting the operation of the semiconductor devices.
Furthermore, precursors that are used in the CVD and ALD processes have disadvantages in that they are decomposed upon exposure to the air due to their instability, increase maintenance costs and production costs due to their high costs, and reduce productivity (throughput). As used herein, the term “precursors” refers to single organometallic compounds prepared by bonding organic ligands to metals, which undergo a phase change under specific conditions and are used mainly to form thin films (such as pure metal films, metal oxide films or metal nitride films) on wafer surfaces by decomposition of organic ligands.
Precursors comprising silane-based polymers, which are currently used, have a disadvantage in that they are not suitable for use in semiconductor processes, because they fail to provide a sufficiently low dielectric constant, or the mechanical properties of films formed using the precursors are poor, or the content of organic carbon in Insulating films formed using the precursor is high.
Particularly, polymers such as tetramethoxysilane or tetraethoxysilane have problems in that the content of organic carbon in insulating films formed using the polymers is high and in that the polymers have a high moisture absorption rate that greatly increases the dielectric constant, even though the polymers have high mechanical properties. Due to these problems, the use of the polymers as insulating films is limited.
Accordingly, in the technical field to which the present invention pertains, there is an urgent need for the development of precursor materials for filling fine gaps, which can be prepared by an SOD process and have a low dielectric constant, excellent mechanical properties such as modulus, excellent compatibility with pore-forming materials, and greatly improved process applicability.